Process for forming sheet glass



T, C. MCKXNLEY PROCESS FOR FORMING SHEET GLASS Filed Jan. 18. 1926INVENTQ'H mama.: 1m/wle;

' 'ATTDNE i'atented Oct. 25, 1927.

A UNITED. STATES PATENT OFFICE.

THOMAS C. MGKINLEY, OF CHARLESTON. WEST VIRGINIA. ASSIGNOR TO LIBBEY-OWENS SHEET GLASS COMPANY, 0F TOLEDO, OHIO, A CORPORATION OF OHIO.

PROCESS 'OR FORMING SHEET GLASS.'

Application filed January 18, 1926. Serial No. 81,925.

The present invention relates to a process` for producing glassarticles.

An in'iportantobject of the invention is to provide a process whereinglass articles are formed from a source of supply made fromV of supplywhich may be refined and used to produce the desired articles. 0

Still another object of the invention 1s to provide a process,particularly well adapted for the production of fiat drawn sheet Iglass`and more specifically includes means for forming cullet, said culletbeing remelted to form a mass of molten glass from which the sheet maybe drawn, this latter mass of glass being formed from cuhet only, andpreferably cullet from the same batch. v

ther objects and advantages of the invention will becomeapparent duringthe course of the following description.

In the drawings wherein like numerals are employed to designate likeparts throughout the same,

Fig. lis a vertical longitudinal section of a form of cullet producingapparatus which may be used, and A Fig. 2 is a vertical longitudinalsection of a form of sheet glass apparat-us.

It is common practice in the ,prior art to produce' a source of moltenglass by melting a batch which includes some raw materials and somecullet. In the various processes the percentage of cullet'varies.

In the drawings, especially in Fig. 2, a type of' furnace and tank whichhas been used in connection with the Colburn machine is illustrated. Inpreparing glass for the Colburn machine it has been found that thequality of glass can be improved after it has started to run bad byadding a slightly higher percentage of cullet than originally. It hasalso been found that cullet which is not foreign cuilet gives the mostbeneficial re suits.

In the Colburn machine the glass hatch is introduced at one end of atankfurnace, where it is subjected to an intense heat to melt theingredients of said batch. The molten glass thus formed is permitted toHow through thel refining end of the tank, after which it passes througha cooling chamber and into the pot from which the glass'is drawn insheet' form. Some of the glass is skimmedofl of the molten mass beforeit is drawn into the sheet, and this' skimmed glass is ordinarilysubjected to the action of cold water which transforms the molten glassin'to cullet. In addition to the cullet lformed in this manner,considerable glass is trimmed ofi' from the sheet and this -is alsoknown as cullet. Cullet used in thc batch, which was originally producedfrom the same tankis much better than cullet taken from some other tanknot. using the same batch makeup.

In the present application a process is set forth wherein nothing butcullet is used to create a mass of molten glass from which the sheet maybe drawn.

In Fig. 1 a form of tank furnace 5 is' shown wherein the end 6 is themelting end, and the end 7 is the refining end. The raw materials orbatch -8' is introduced within the dog-house 9 by means of a spout 10.The batch 8 floats upon the molten glass 11. and is subjected to heatintroduced through the regenerators 12. The molten glass then flowsthrough the refining end and is permitted to overflow a lip 13 upon anendless conveyor 14. A jet of cold water 15. is brought to play upon thehot glass as it; overflows the lip, which causes the glass to becomesolidi-1 fied and broken up into cullet 16. It is to be clearlyunderstood that the arrangement shown in Fig. 1 is purely diagrammatic,as any form of tank can -be used to produce the cullet.

The cullet 16 is then placed in a suitable receptacle having connectionwith a spoilt 17, so that at intervals the cullet 16 may be dischargedin the floghouse end 18 of the tank furnace 19. The cullet. 16 floatsupon the molten glass 2h in thi` furnace 19 where it is again subjectedto the action of rcgenerators 21. The molten mass then flows through therefining end E22, coolingkhamber 23, and out into the draw-pot 2l. fromwhich a sheet 25 may be continuously drawn. By using this process. theamountof dust. and dirt, which has heretofore been prevalent in theglass tank. is practically entirely eliminated. The various ingredientsused in the hatch 8 in Fig. 1 are casi ly blown about as they arechiefly in powder form. On the other hand the cullet 16 nothing more,than pieces of broken glass which is los easily melted. The glassentering` the draw-pot- 24, when formed vtrom cuilleis of a betternature than the glass overflowing the lip 13 in Fig. 1. thuspern'iitting a wider sheet-to be drawn at a faster rate than heretofore.lt is believed that all of the ordinary troubles encountered in themachines using molten glass formed by the usual practice will be greatlyreduced. e

By using cullet to form the mass ot molten glass from which the sheet'is drawn. it is possible to obtain unifori'n inciting conditions and tohold Ltuch conditions. ln the operation of the Colburn machinev as' nowused, when defects turn up in the sheet, it. is customary to makevarious changes all along the. line down to and includiir;r the melting:end to orerccnne the troubles with' the sheet being drawn. Thesevariations. although necessary at the time to improve the sheet. are.not beneficial to the ;lass beingr melted. As tht` eullet is remarkablyconstant in its nature :is regards meltingr conditions. it will rarelyhe i'iecessary to vary the melting end to take care. of variations inthe drawing machine operation.

In addition to the possibilities` of uniform meltinrr conditions. itisto be noted that. the

action ot the hatch ordinarily used is rery corrosive on the tank blocksduring the melting, which necessitates shut-downs for cold repairs'atrelatively frequent intervals'. On the other hand, in remeltinf; eullet.the corrosive action is much less and the tank furnace, from which the,sheet source is supplied, will have a much longer life thanv when theraw hr-.teh is melted as at present.

In view of these advantages. it isV not necessary to interruptproduction of the sheet. glass as often as has been customary.()ccasionally, due to either imperfect melting conditions or mixtures inbatch composition, defective glass is produced, and in such a case whencullet. is beingr produced, tlyis matter can be caught and the. hadcullet returned to the tank for remelting after the conditions whichceased the formation-'of poor cullet has been corrected. Of course it isto be understood that suitable connections can be had between the culletproducing'ntachine and the tank furnace which remell's tfiiecullet, thatis, the glass can tlow `from the tirst melting tank directly into theYtank furnace without being`entirely chilled. thiis" .Saving consisting4in melting cullet only to a certain extent the amount of fuel requiredin the remelting. The invention eon sists in the idea ot using culletfor the purpose of forming molten glass from which a sheet. may hedrawn.

It. is to be understood that thc form of the invention herewith shownand described is to be taken'iasfthefpre [erred Yembodiment of thesame-.fand that various changes in the shape.:-i7.e and arrangement ofparts may be resorted to without departing from the spirit of theinvention or the. scope of the subjoined claims.

l claim:

1. That step'in the process of producing a Jglass article. consisting inIforn'iinf;r a. molten source of supply from cullet only.

if. The process of producin r a glass article. consisting;r inassembling a rair hatch of materials. meltinglr the hatch. causingY the.molten glass bythe act of cooling to solidify in partir-lev form. andthen reniclting the same to form a molten source of supply from whichthe article may he made.

3. 'I`he process of producingA sheet glass. consisting in mcltnfrculletonly toorm a uniss of molten glass. retining: the. same, and tllenfoi-tiling :i sheet from said molten glass.

Ll. The process of producingsheet glass.

-inass et' molten glass, and then i rawingr a sheet therefroni. l'

5. The process ot producingr sheet lglass,

',"consistimgr in melting a ran' batch of imitefrials to form moltenglass. permitting the glass to become hardened' in particle form, andthen using,r this hardened particle glass to form a mass of molten glassfron'iarhich the sheet may he drawn.

6. As a new article of manufacture. a sheet of =fglass made fromrenielted ciillet only.

7. The process of producing a glass article consisting in melting,r arow hatch of nia.'- terials to form molten glass, cooling said glasshereby to cause it to solidify in particle form, and then forming amolten source of supply from these soliditied particles only.

Signed at Toledo, in the county of Lucas, and State of Ohio, this 14thday of Janu ary, 1926. i

THOMAS C. MQKINLEY.

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